Render invitation email without a layout

Ideally, we'll probably want to add a layout for this email at some point,
but this simplifies it to the bare minimum and gets rid of the "click here
to change your notification settings" link.

fixes #3270

resolve reshare authors to the first one

updated webmock, hopefully fix cucumber

make federation logger db creation faster by not migrating but using the schema instead

This reverts commit e5206f34.

Translation invitation Share this link /stream [ci skip]

This reverts commit c52342b7.

[Rebase] Add translation app/views/admins/stats.html.haml for Admin Panel [ci skip]